1. Field of the Invention
The present invention relates to a method and apparatus for recording and reproducing various signals and more particularly to a recording/reproducing method and apparatus therefor which are suitable for recording and reproducing a signal scrambled so as to prevent interception.
2. Description of the Prior Art
An addressable CATV system which is described in "AV Products with Digital Technology" under the supervision of Fujio Mari, Corona, Ltd. is an example for sending a signal which is scrambled so as to prevent interception. In such a system, a viewer receives key information for descrambling from the CATV station, descrambles a signal by a decoder, and views a television receiver.
When a viewer has a want to view a broadcasted program later, a video signal of the descrambled decoder output is recorded on a VTR. By doing this, the viewer can view the recorded program later. On the other hand, for the CATV station, there is a problem imposed that there is a possibility that a program which is distributed for specified viewers with payment is viewed by the public at an optional location without payment. This means that the scrambling for interception prevention is not effective. Therefore, the CATV station gives protection to the decoder output so that it may be outputted on a television receiver but cannot be recorded on a VTR. By doing this, there is another problem imposed that the viewer's want to view a broadcasted program later instead of right now cannot be satisfied.
As mentioned above, the prior art has a defect that, for example, the request of the CATV station and the request of a viewer cannot be satisfied at the same time.